The purpose of this research study is to evaluate the potential clinical effectiveness of an investigational drug called DMP 777 for treating joint pain in patients with systemic lupus erythematosus (SLE). DMP 777 is an investigational drug whose main activity is to block or inhibit the activity of a specific molecule, called elastase, which is contained inside a specific inflammatory white blood cell, called a neutrophil. DMP 777 is classified as a neutrophil elastase inhibitor. Inhibition of neutrophil elastase may be important in alleviating pain, tenderness, and swelling in the joints of patients with SLE. The purpose of this study is to determine whether 14 days of treatment with DMP 777 can improve active joint signs and symptoms in patients diagnosed as having SLE. DMP 777 is contained within a capsule which is taken by mouth.